Wildlife biologist John Deshler headed up the study and said the aim wasn't just to come up with numbers, but also to see if certain species are abundant or if they are facing any threats, and of course to gain an understanding of what's there for future research and management efforts at the park.

"Some species that are gone today may be good candidates for reintroduction," Emily Roth, senior environmental planner for Portland Parks & Recreation, said in a news release about the study. "And there is still much to learn about insects in Forest Park. It is possible that there are thousands more species than the ones we know about at this point."

Researchers found 45 species of mammals at Forest Park including shrews, chipmunks, skunks, porcupines, elk, bobcats, coyotes, weasels, 10 types of bats and the rare mountain beaver (native only to the Northwest and previously unseen in the park for decades).

They also found 104 bird species including owls, woodpeckers and bald eagles. Nearly three dozen of the common bird species at the park are in decline and other bird species, like the grouse and quail, have disappeared altogether.

And finally, over 400 invertebrate animal species were found - mostly beetles and moths.